Western Digital (NASDAQ: WDC) experienced a sharp sell-off on Thursday, with shares declining 10.8% to $458.22 in afternoon trading. The drop erased approximately $19.2 billion from the company's market capitalization, a figure that amounts to roughly 5.2 times its quarterly revenue guidance of $3.65 billion. The move comes as the broader AI-storage trade loses steam, with the Philadelphia semiconductor index falling 3.5% around midday.
The decline was particularly notable given Western Digital's recent transformation into a pure-play hard-disk drive (HDD) company following the separation of its flash memory business into Sandisk (NASDAQ: SNDK). Despite this strategic shift, the stock is still trading like a memory chip name, amplifying its sensitivity to shifts in AI demand sentiment. The drop also exceeded that of direct HDD rival Seagate Technology (NASDAQ: STX), which fell 9.0% to $753.65, and memory chip maker Micron Technology (NASDAQ: MU), which declined 6.4% to $846.31.
Western Digital's underperformance was stark: it fell 1.8 percentage points more than Seagate and 4.4 points more than Micron. The stock is now 17.5% below its Monday close of $555.55, marking a rapid de-rating just weeks before its fiscal fourth-quarter earnings report, scheduled for release after the market close on August 5.
The $19.2 billion market value loss is not a cash-loss comparison but rather illustrates how heavily Western Digital's valuation depends on long-term AI demand projections. The company's operating results had been strengthening prior to the sell-off, with fiscal third-quarter revenue rising 45% year-over-year to $3.34 billion and non-GAAP gross margins reaching 50.5%.
Chief Executive Irving Tan had expressed optimism in April, stating that "virtually every AI workload" creates data that requires persistent, cost-efficient HDD storage. Thursday's price action does not disprove that demand thesis, but it suggests investors are reassessing the premium they are willing to assign to the duration of that growth.
Sartorial Wealth Chief Executive Shiraz Ahmed commented to Reuters that "the chip rally is cooling off," noting that AI adoption remains uneven while infrastructure spending continues to be heavy. This sentiment appears to be weighing on the entire AI-storage ecosystem.
The next major catalyst for Western Digital will be its August 5 earnings report, where investors will closely watch revenue, margins, and forward guidance for signs of sustained demand. Key risks include a slowdown in AI investment that could weaken pricing and volume expectations, while tighter HDD supply or stronger cloud orders could quickly reverse the decline.
